Frame bracing, boxing vs tubing.

[Spiff]

How does the sump of the engine fit with those braces between the fram rails??

I have now made two gussets, they fit fine but because of the pet cock the left had to be massaged extensively with a hammer and the right one a little bit so the tank could shift a little bit to the left so the petcock can clear when lifting the tank up and down.
I could have chosen not to do this but that would mean I would have had to remove the petcock every time I had to lift or remove the tank and for a show bike sure, but I plan on using this so servicing needs to take priority

[Nessism]

I recall from back in the day that using thicker engine mount plates helped beef up the stiffness. No personal experience just sharing...

[kochic]

How does the sump of the engine fit with those braces between the fram rails??

I have now made two gussets, they fit fine but because of the pet cock the left had to be massaged extensively with a hammer and the right one a little bit so the tank could shift a little bit to the left so the petcock can clear when lifting the tank up and down.
I could have chosen not to do this but that would mean I would have had to remove the petcock every time I had to lift or remove the tank and for a show bike sure, but I plan on using this so servicing needs to take priority

Good work, I will follow your build.
The last pic I posted is not the lower frame rails, this is the front lower tubes.
Marc

[limeex2]

Great thread. thank you for the pics, links and advise.

[Spiff]

Making some slow progress, but I have some questions about the headstock bracing! See bottom picture:






A is how the sketch is outlined on the katana fram scheme I posted in my first post, but that interferes with the rubber grommet for the tank so I have to think of something else.
I can do B with steel plates, C would also work with 12mm tubing(that's a hair under 1/2") and I think I might also get D to work without it interfering with the tank. Maybe.
What do you think is the best? I think B and D with C being more of a compromise

[salty_monk]

B probably will look better and is more like the bracing they put on modern frames... I also like the fact it is braced counterclockwise as any bumps etc are going to put forces in that plane aren't they?

[GregT]

For me - and I've stayed out of this lately because everyone has to make their own mistakes - all that's needed is the lower diagonal in D.
I wouldn't do any more welding on the headstock itself - it is stiff enough already IMO.

What you're trying to do is stiffen the area of the frame where the headstock loads are transmitted downward. The top tubes with your stiffeners will be more than adequate.

Bear in mind my experience is with big fours in tube frames being roadraced on slicks. Including a very quick GS1000 used on bumpy street circuits.
Budget for some really good rear shocks - and don't overspring them.

[Spiff]

Hmm... I thought the object of this brace was to prevent the headstock from twisting forces primarily?

As for dampers I have a set of öhlins dampers from a gsxr1400. Not sure on the springing they might be to stiff I will have to see once the bike is assembled fully. I plan on complimenting them with some new springs in the front fork as well as they seemed soft, might be able to take some of it off with the preload adjustment idk

[salty_monk]

Run some straight weight springs around 0.9kg/mm and cartridge emulators if you're using stock forks...

[GregT]

Hmm... I thought the object of this brace was to prevent the headstock from twisting forces primarily?

Reply...If you make the headstock very stiff - but feed the loads into a flexible frame, where's the gain ? In roadracing situations, the heaviest loads coming from this area are actually braking loads. When you see -up close - a group of big pre 82 racebikes having a braking duel into a downhill hairpin on a bumpy street circuit, the light dawns.....

As for dampers I have a set of öhlins dampers from a gsxr1400. Not sure on the springing they might be to stiff I will have to see once the bike is assembled fully. I plan on complimenting them with some new springs in the front fork as well as they seemed soft, might be able to take some of it off with the preload adjustment idk

Little story....We bought Gazi shocks for the 1000. Very good quality and about 1/2 the price of Ohlins. Very popular in Post Classic racing in Australia and well supported too.
AFAIK we're the only Gazi users to buy the softest option spring available. It's perfect on the 1000 with a light/medium rider. We actually have measurable sag.
I'm told that nearly all the posties racing in Aus have no static sag at all.....

[Spiff]

Run some straight weight springs around 0.9kg/mm and cartridge emulators if you're using stock forks...

I'm not, I will be running sv1000s forks. So I'm not sure on the spring weights I guess I'll just have to get the bike together and see how it behaves and how it sags and such.

Little story....We bought Gazi shocks for the 1000. Very good quality and about 1/2 the price of Ohlins. Very popular in Post Classic racing in Australia and well supported too.
AFAIK we're the only Gazi users to buy the softest option spring available. It's perfect on the 1000 with a light/medium rider. We actually have measurable sag.
I'm told that nearly all the posties racing in Aus have no static sag at all.....

Yeah I mocked everything up and when I sat on the bike there was no sag at all from the öhlins, so that's why I think they might be too stiff. I didn't check if there was any preload added on them so like I said I'll just have to get the bike together and take it from there...

[kochic]

I'm looking to get YSS shocks for my gs.I only heard good thing about them for the price.
I made little progress today.
Marc
CIMG5600.jpg

[Spiff]

Moving along ever so slightly...

[kochic]

Thanks for the update,
Marc

[Chuck78]

Good thread, subscribing. I need to do this to my 750 this year... Will definitely be doing tgis extensively to my GS400 489cc track bike this year.